Did a job for the neighbour of a work colleague 13(I think) years ago when I was in college doing my first plumbing course.
It was to remove a downstairs cloakroom, the hot and cold were fed down from the ceiling cavity and I cut them and put 2 John Guest speedfit stop ends on, then proceeded to remove the basin and W.C.
Got a mate to mortar a couple of bricks in the hole were the soil was and put a 4'' cap in the soil spigot after removing the old soil from the loo. I was pleased as punch with the job.
Fast forward to last summer - got a call to install a cloakroom, went round and recognised the house, I knew I'd worked there before but wasn't sure when or what it was I did there, the lady of the house didn't recognise me either.
Anyway she explains that there used to be a cloakroom and she wants one putting back, has a look and remembered the job, looked up and those 15mm JG stop ends were still there holding fine.
In the process of doing the job I found the McDonald's wrapper in the cavity where my mate had bricked up the hole, he's rough as sandpaper that lad 😉 /irony
TLDR: I know they 'can' last 13 years without problems 🙂